i didn't change the commands - stayed with default names.
i did not put a space or enter after the command in the SMS message, however, when i open the SMS message in the N900, the message looks as if there is a new line (as if i also added an ENTER key to the end of the message).
my device language is English(United Kingdom).
One more thing is that i did not use another cellular to send the SMS - i used a windows application called "TextMe" - i don't have another cellular to use for sending.
i also tried to copy the message content from the N900 after i got it to clipboard and paste it to a new sent SMS message and it didn't work also.

Thanks.